In general, when an image forming apparatus is used which makes it possible to copy onto a large-sized sheet such as A0, A1, etc., if such a large-sized sheet is stored as it is or if the large-sized sheet is handled as it is, a storage space ends up becoming large, or handling thereof is inconvenient, so that normally the sheet is folded for storing and handling.
However, if a sheet folding operation is performed manually, a significant amount of time is needed, so that a time required for folding a sheet may end up being longer than a time required for copying.
In light of the above, there is a system in which is arranged, in a sheet discharge path of an image forming apparatus, a sheet folding apparatus which can fold a sheet automatically, making it possible to automatically fold in succession large-sized sheets copied (Patent Documents 1-4).
In a sheet folding apparatus for use in such a system, there may be included a unit (an off-line operation) for folding a sheet which was inadvertently copied and discharged without folding in advance, or a large-sized sheet which was produced by a different image forming apparatus, etc., as well as (an on-line operation of) automatically folding a sheet discharged from an image forming apparatus.
When paper folding is actually performed by such a system, for a standard-sized sheet such as A0, A1, etc., paper folding can be performed using a predetermined size for each face of a sheet to be folded. In an image forming apparatus which can copy onto the large-sized sheet, copying may be performed onto a long sheet such that a length in a sub-scanning direction amounts to several meters, so that it is required to perform paper folding even for such a non-standard long sheet.
A paper folding apparatus disclosed in Patent Document 1 automatically adjusts a folded length of each folded portion to fold even a sheet other than one having a standard length to a specified dimension. Patent Document 2 discloses a paper folding method and a paper folding mechanism that orderly form a folding edge in a desired folding mode, while Patent Document 3 discloses a paper folding machine which ensures that unnecessary folds are not produced when a folded sheet is discharged. Patent Document 4 discloses a paper folding apparatus which reduces unevenness in a folding dimension even for a large-sized sheet whose tip is curled.
Below, an explanation of an image forming apparatus and a sheet folding machine according to a related art is provided in accordance with a schematic configuration indicated in the drawings.
FIG. 1 is a diagram showing a schematic configuration of a related-art image forming apparatus to which the present invention is applied as well a schematic configuration of an image forming apparatus which shows one embodiment of the present invention. In FIG. 1, a number 200 denotes a copying machine, which is one form of an image forming apparatus body. A number 300 to which parentheses are affixed is an example of a related-art sheet folding machine which is arranged in a sheet discharging path of the image forming apparatus body 200, while a number 500 to which parentheses are affixed is an example of a related-art sheet folding apparatus. A number 1000 to which parentheses are affixed denotes a related-art image forming apparatus or image forming system in which a related-art sheet folding machine 300 is connected and mounted to the image forming apparatus body 200.
In FIG. 1, with respect to numbers to which parentheses are not affixed, a number 50 is a sheet folding machine which shows one embodiment of the present invention; a number 1 is a sheet folding apparatus which shows one embodiment, etc., of the present invention; and a number 100 is an image forming apparatus or image forming system which is configured with a sheet folding machine 50 to be a post-processing apparatus being mounted to the image forming apparatus body 200.
In the image forming apparatus body 200, a sheet P which is fed from a paper feeding unit 209 or a manual paper-feeding unit 208 is conveyed by a fed-paper conveying unit 210, and an image is formed thereon by an image forming unit 220, after which it is discharged out of the image forming apparatus body 200 by a discharged-paper conveying unit 230. The sheet P, which is discharged out of the image forming apparatus body 200, enters a sheet receiving unit 21 of the sheet folding machine (300) that is arranged in a sheet discharging path of the image forming apparatus body 200, and is conveyed to the sheet folding apparatus (500) by the feeding unit 20.
The sheet folding apparatus (500) includes a conveying roller pair 3; a first folding roller pair 6 and a second folding roller pair 7 that are arranged in an opposing manner to the left and the right of a lower portion thereof; a first sheet guiding member 4 and a second sheet guiding member 5 that selectively guide a sheet P conveyed from the conveying roller pair 3 in each folding roller pair direction; and a lower sheet face guide 10 which guides a lower face of the sheet P. The sheet P is fed by the conveying roller pair 3 and conveyed, and selectively guided to the first folding roller pair 6 or the second folding roller pair 7 by an operation of the first sheet guiding member 4 or the second sheet guiding member 5. The guided sheet P is folded a predetermined number of times by being fed between the first folding roller pair 6 or the second folding roller pair 7 while sliding on an upper face of the lower sheet face guide 10 by an operation of the first sheet guiding member 4 or the second sheet guiding member 5 in alignment with repeating of forward and reverse rotations of the first folding roller pair 6 and the second folding roller pair 7. In FIG. 1, a number 2 denotes an inlet sensor which is to be a sheet detecting unit which is arranged between the feeding unit 20 and the conveying roller pair 3 and which detects a tip of the sheet P which is conveyed from the feeding unit 20. The inlet sensor 2 is to be a trigger signal for operation control at and after the detecting time. Moreover, toward the right in an upper portion of the sheet folding machine (300) is arranged a manual insert tray for placing thereon and feed a copied sheet P, for example.
However, in the above-described related-art sheet folding apparatus (500), the sheet P is folded a predetermined number of times by being fed between the first folding roller pair 6 or the second folding roller pair 7 while being slid on an upper face of the lower sheet face guide 10 by an operation of the first sheet guiding member 4 or the second sheet guiding member 5 in alignment with repeating of forward and reverse rotations of the first folding roller pair 6 and the second folding roller pair 7, so that a resulting state thereof becomes a zigzag fold.
As described above, in the related-art sheet folding apparatus (500), the sheet P is folded alternately by the first folding roller pair 6 and the second folding roller pair 7. Thus, while folding is possible without being affected by the length of the sheet or the number of times of folding, it is only possible to alternately perform trough folding in which folding is performed with an image face facing inside and crest folding in which folding is performed with an image face facing outside, and it is not possible to successively perform trough folding or to successively perform crest folding.
Even in folding methods described in JIS (Z8311: Technical Drawings-Sizes and Layout of Drawing Sheets, Appendix (Reference): Standard Methods of Folding Drawings) that are generally well known drawing sheet folding methods is included a folding method in which crest folding is repeated. A folding finishing state shown in FIG. 2A is a state in which an A0-sized sheet is folded, resulting in basic folding, which is described in JIS in the above. In this case, crest folding is performed twice with a title column facing up. Moreover, in a similar manner, with respect to A0-sized bag folding, crest folding is performed twice with the title column facing up. This folding, which cannot be handled by the related-art sheet folding apparatus, is handled by performing crest folding and trough folding from the title column side as shown in FIG. 2B.
Besides the foldings described in JIS, there are folds which require finishing in which there are successive folds in the same direction; these are folds which are often used in notices, brochures, etc., such as an inner three fold as shown in FIG. 3A and a gate fold as shown in FIG. 3B. However, the related-art sheet folding apparatus cannot handle these common folding specifications, so that specification is changed, or folding is done manually.